Automatic Dependent Surveillance-Broadcast (ADS-B) is an international aviation system recently defined and implemented where aircraft use GPS information to determine their position and broadcast it in short (112 bit) bursts of 120 microseconds duration transmitted at nominal 1 second intervals. The frequency used to transmit the messages, 1090 MHz, is the same frequency used by aircraft transponders to respond to interrogations from ground based surveillance radars or interrogations from airborne collision avoidance systems (TCAS/ACAS). The ADS-B transmissions may be monitored by other aircraft equipped with ADS-B IN receivers or by ground stations within up to 100 NM range to acquire, track, and display the location of other aircraft.